Xiaomi 4 handwriting screen sometimes can't write words. What's the matter?

The screen of Xiaomi mobile phone 4 is: 5-inch Sharp /JDI high color saturation display 1920 x 1080 pixel resolution, and 44 1 PPI high sensitivity touch screen.

What should I do when the screen of Xiaomi mobile phone 4 fails?

1. If the screen touches abnormally when the mobile phone is charging or connected to the power supply, for example, when it is connected to a computer through a USB cable, then we need to see if it is caused by unstable voltage, or if the data cable and charger used are not originally adapted.

2. Click System Tools → System Update → Update System on the main page of the mobile phone; Try to upgrade the mobile phone system to the latest version.

3. Calibration screen:

3. 1. Enter * # * # 6484 # * * in the dial-up interface to enter the hardware detection mode;

3.2. Slide down the hardware detection interface to find the touch screen test, and click Enter;

3.3. Long press the leftmost virtual key (three horizontal keys) in the touch screen test interface, and select touch calibration in the menu that appears;

3.4. On the next page, there will be an option to start calibration. After clicking OK, do not touch the screen until the prompt of successful calibration appears.